The present invention relates to radio-frequency antenna systems, and particularly to antenna systems having broad-band characteristics.
Resonant-element type antennas, such as the conventional monopole, dipole, loop, or transmission-line types, have impedance characteristics which vary greatly with frequency, and therefore are normally used only as narrow-frequency band antennas. Wide band antenna systems are usually of the non-resonant type, e.g. cylindrical, conical, spheroidal, diamond, logarithmic, but these usually require substantially large sizes, particularly for the VHF and UHF ranges.
An object of the present invention is to provide a radio-frequency antenna system having both broad-band monopole antenna characteristics and also relatively small physical size.